Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Neuroblastoma is a neoplastic disease of infants and early childhood and is the third most common malignant cancer tumours in paediatric patients. Approximately 80% are found in children under 5 years of age. Elevated values of homovanillic acid (HVA, a metaboloite of dopamine) and HMMA/VMA (a metabolite of metadrenalines), may be suggestive of the presence of neuroblastoma. HVA and HMMA/VMA can be used for the diagnosis and follow up treatment of neuroblastoma. Early studies showed that the long term survival rate of these patients could be readily diagnosed using HMMA/HVA ratios.
Specimen container paediatric:
Random urine collection: white universal container [sent to lab immediately]
Specimen container adult:
Test not available for adults
Minimum volume paediatric:
1 – 10 mL urine
Minimum volume adult:
N/A
Special requirements:
This test (in conjunction with HMMA) is only used for neuroblastoma screening in children. To test for phaeochromocytoma, measure plasma or urine metadrenalines.
Sample stability:
Once pH has been adjusted to 3.0 to 3.5, samples are stable at 4°C for up to 10 days. For long-term storage, store samples at –20°C.
Transport requirements:
Ambient temperature.
Interpretation:
Homovanillic acid (HVA) and/or HMMA/VMA concentrations are elevated in over 90% of patients with neuroblastoma; both tests should be performed. A positive test could be due to a genetic or nongenetic condition. Additional confirmatory testing is required. A normal result does not exclude the presence of a catecholamine-secreting tumor.
Elevated urinary HVA values are suggestive of a deficiency of dopamine beta-hydrolase, a neuroblastoma, a pheochromocytoma, or may reflect administration of L-dopa.
Decreased urinary HVA values may suggest monamine oxidase-A deficiency.
Reference ranges:
0 – 1 year: 3.0 – 25.0 µmol/mmol creatinine
1 – 3 years: 3.0 – 25.0 µmol/mmol creatinine
3 – 6 years: 2.6 – 13.0 µmol/mmol creatinine
6 – 10 years: 2.4 – 7.0 µmol/mmol creatinine
10 – 16 years: 1.0 – 6.0 µmol/mmol creatinine
Adults: 0.8 – 35.0 µmol/mmol creatinine
Factors affecting result:
Urine sample must be sent to the lab immediately, to be frozen upon receipt
Administration of L-dopa may falsely increase HVA results. Patients receiving L-dopa should stop taking it for 24 hours before and during the collection. All patients receiving L-dopa should be identified to the laboratory when HMMA and HVA tests are ordered.